1. Field of Disclosure
The present disclosure relates to a circuit. More particularly, the present disclosure relates to a voltage trimming circuit.
2. Description of Related Art
The reference voltage in a circuit, such as a low drop out linear regulator, has to be very precise. However, the reference voltage generating circuit may suffer from many undesirable effects resulting in an inaccurate output voltage. Thus, a trimming mechanism is needed to tune the inaccurate output voltage back to the desired value of the output voltage to provide the accurate reference voltage.
Nevertheless, the conventional design of the voltage trimming circuit provides only up-trimming mechanism to up-trim an initial output voltage from a value lower than the target output voltage. Once the initial output voltage is higher than the target output voltage, the up-trimming mechanism fails to reach the target output voltage. In addition, if the initial voltage with lower value is generated first, it may have to take more bits of trimming voltage steps to reach the target output voltage. Thus, the more bits of trimming voltage steps it takes to trim the output voltage, the more the LSB error will be generated.
Thus, what is needed is a voltage trimming circuit provides both up-trimming and down-trimming mechanism. The present disclosure addresses such a need.